The invention relates to a ship loader or unloader including a boom supported in the region of a portal and a feed head which cooperates with a loading or unloading device disposed in the region of the forward end of the boom on the side of the ship, the feed head being movable on an upper and a lower track in the region of the boom and being equipped with an associated supply and discharging device. The upper track is provided in the region of the forward end of the boom and the lower track is provided in a platform-like region of the rear portal-like boom end.
German Patent 1,202,221 discloses a portal-like supporting device for a ship loader, with the device including a pivotal boom equipped with a discharge conveyor belt. The free end of the boom is suspended from a frame pylon so as to be raisable and lowerable. Between the frame halves there is disposed the boom which supports a discharge conveyor that can be pulled in and extended. One end of the boom is supported on a console in a bearing having a pivot axis oriented in the direction of travel, while its other, free end is suspended from cables which are brought over the tip of the pylons to lifting mechanisms in a machine house disposed at the pylons.
A drawback in addition to the heavy weight of the structure of the overall system is that enormous forces and moments occur in the region of the travel track of the discharge conveyor when the latter approaches its extended end position. Moreover, the components are almost inaccessible, particularly during operation, for monitoring and maintenance purposes so that the system must first be stopped to perform the necessary work.
A structurally similar device is disclosed in German Utility Model Patent No. 74/07,046. The boom arm is composed of a supporting frame which is movable in the longitudinal direction of a bridge that is ascendingly guided and is supported in a supporting portal so as to be rotatable on one side about a vertical axis and pivotal in height about a horizontal axis, with the supporting frame accommodating a transporting conveyor. In order to be able to move the supporting frame within the portal bridge, the latter is provided with truck rollers, with displacement being effected by means of a drive. Particularly with respect to the displacement of the supporting frame, the same arguments apply as described above. Moreover, a relatively complicated frame structure is required here in order to absorb and dissipate the forces.
Due to the structurally complicated and necessary measures in order to master the forces and moments generated during the extension of the feed head (supporting frame, discharge conveyor), the system must be made relatively heavy which ultimately results in increased costs.
For static reasons, ship loaders or unloaders employed in practice have been designed as follows:
For a feed head of, for example, a capacity up to 6000 t/h, welded carriers of a height of approximately 1.6 m have been provided with the most varied reinforcements. The boom itself is composed of welded carriers of a height of about 3.5 m and equipped with a plurality of buckling reinforcements. The belt contact disposed within the boom and the support and drive for the feed head were accessible only in a complicated manner so that necessary repair and maintenance work was possible only with large expenditures of time and money.
Such a system as described above is disclosed in the periodical "Fordern und Heben" [Conveying and Lifting], Volume 18 (1968), No. 13, pages 803 and 804, and corresponds to the species defined in the preamble of the first claim. The boom here has a box shape, with its walls being formed by a plurality of interconnected struts to which wind deflecting metal sheets are attached. Within the boom there is disposed a stationary belt equipped to transfer to a horizontally movable belt conveyor (feed head). In the region of the free boom end, there is disposed a charging head which can be raised and lowered by means of a winch provided on a carriage, with the carriage being movable within the box on separate guide rails in such a manner that the carriage is connected by way of connecting pipe with the movable conveyor and thus is displaced by the latter. The drawbacks of such a system have already been described above. Additionally, this system is of the stationary type and, when seen over the length of its boom, offers a large area of attack to the wind since the system cannot be pivoted upwardly relative to the actual device.